The basic circuitry of a conventional pocket telephone dialer is shown in FIG. 1. FIG. 1 schematically illustrates a prior art dialer circuit 10 for a Dual Tone Multifrequency (DTMF) telephone which comprises dialer chip 12, crystal 18 and loudspeaker assembly 17. Generally, all DTMF telephone push-button tones ("0-9", "*" and "#") have tone frequencies that are multiples of a base frequency generated by crystal 18. Typically, dialer chip 10 includes a tone generator having a memory (which stores a plurality of telephone numbers that the user has programmed), two frequency multipliers, and a frequency adder (not shown).
To generate each push-button tone, the base frequency is multiplied in one multiplier by a predetermined amount that varies for each of the four keypad rows and the base frequency is multiplied in the other multiplier by a predetermined amount for each of the three keyboard columns. These predetermined amounts are stored in the memory for each row and column. The two multiplied frequency tones are then combined in the adder to produce the DTMF standard tone for each push-button. The combined frequency tone from dialer chip 12 is supplied to loudspeaker assembly 17 which includes a driving transistor 15, having a ground Vs at the emitter and a speaker 14 at the collector.
In operation, the user can recall a pre-programmed telephone number using a predetermined push-button(s), and the like. The tone data of the selected telephone number are outputted from the memory to speaker 14, which is placed over the mouthpiece of the telephone to dial the selected telephone number.
However, it is often desirable to not only output tones representing telephone numbers to place a call, but to also output a speech synthesized message to the user and/or to the receiver of the telephone call. For example, the party's name that the user is calling may be vocalized to confirm that the user is calling the correct party. Further, once the telephone call is connected, a selected synthesized message may be outputted, so that the user need not talk to the called party. This feature is especially useful for users having speech impairments or a limited language vocabulary.
It is therefore an object of the present invention to provide a telephone dialer that is capable of outputting telephone tones and voice messages, as desired.
Another object of the invention is to provide two memory stores, one memory for storing the four keypad row telephone tones and the other memory for storing the three keypad column telephone tones of a DTMF telephone to save storage space.
A further object of the invention is to store background sound is one memory and speech sound in the other memory.
Various other objects, advantages and features of the present invention will become readily apparent from the ensuing detailed description and the novel features which will be particularly pointed out in the appended claims.